Fluid communication method for hydraulic fracturing

ABSTRACT

Aspects of the disclosed technology provide techniques for facilitating hydrocarbon extraction from a wellbore. In some aspects, the disclosed technology encompasses a novel casing string that includes at least one casing section, an aperture disposed on a surface of the casing section, and an insert affixed around a periphery of the aperture. The casing string can further include a plug disposed within the insert, wherein the plug is configured to be selectively removable to allow fluid communication between an interior volume of the casing string and an exterior of the casing string, e.g., adjacent to a geologic formation.

TECHNICAL FIELD

The present disclosure relates generally solutions for preventingerosive enlargement of fluid communication holes in a wellbore casingand in particular, to the fitting of casing perforations withwear-resistant inserts to protect against erosion and ensure consistentperforation aperture size.

BACKGROUND

To obtain hydrocarbons such as oil and gas, wellbores are typicallydrilled by rotating a drill bit that is attached at the end of the drillstring. Modern drilling systems frequently employ a drill string havinga bottom hole assembly and a drill bit at an end thereof. The drill bitis rotated by a downhole motor of the bottom hole assembly and/or byrotating the drill string. Pressurized drilling fluid is pumped throughthe drill string to power the downhole motor, provide lubrication andcooling to the drill bit and other components, and carry away formationcuttings.

A large proportion of drilling activity involves directional drilling,e.g., drilling deviated, branch, and/or horizontal wellbores. Indirectional drilling, wellbores are usually drilled along predeterminedpaths in order to increase the hydrocarbon production. As the drillingof the wellbore proceeds through various formations, the downholeoperating conditions may change, and the operator must react to suchchanges and adjust parameters to maintain the predetermined drillingpath and optimize the drilling operations. The drilling operatortypically adjusts the surface-controlled drilling parameters, such asthe weight on bit, drilling fluid flow through the drill string, thedrill string rotational speed, and the density and/or viscosity of thedrilling fluid, to affect the drilling operations.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to describe the manner in which the above-recited and otheradvantages and features of the disclosure can be obtained, a moreparticular description of the principles briefly described above will berendered by reference to specific embodiments thereof which areillustrated in the appended drawings. Understanding that these drawingsdepict only exemplary embodiments of the disclosure and are nottherefore to be considered to be limiting of its scope, the principlesherein are described and explained with additional specificity anddetail through the use of the accompanying drawings in which:

FIG. 1A is a schematic diagram of an example drilling environment, inaccordance with various aspects of the subject technology.

FIG. 1B is a schematic diagram of an example wireline loggingenvironment, in accordance with various aspects of the subjecttechnology.

FIG. 2 illustrates steps of an example process for constructing awellbore casing string, according to some aspects of the disclosedtechnology.

FIG. 3 is a cut-away view of a casing string with multiple casingsections, according to some aspects of the disclosed technology.

FIG. 4A illustrate cut away views example inserts that contain plugs,according to some aspects of the disclosed technology.

FIG. 4B illustrates a cut away view of a wellbore including a casingsection containing an insert, according to some aspects of the disclosedtechnology.

FIG. 5A is a cut away view of a wellbore and a casing string in which adetonating cord is configured to remove a casing plug, according to someaspects of the disclosed technology.

FIG. 5B is a cut away view of a wellbore and a casing string in which anexplosive device is configured to remove a casing plug, according tosome aspects of the disclosed technology.

FIG. 6A is a cut away view of a casing string in which an erosivechemical containment device is configured to remove a casing plug,according to some aspects of the disclosed technology.

FIG. 6B is a cut away view of a casing string in which multiple chemicalcontainment devices are configured to facilitate removal of a casingplug, according to some aspects of the disclosed technology.

FIG. 7 is a schematic diagram of an example system embodiment.

DETAILED DESCRIPTION

Various embodiments of the disclosure are discussed in detail below.While specific implementations are discussed, it should be understoodthat this is done for illustration purposes only. A person skilled inthe relevant art will recognize that other components and configurationsmay be used without parting from the spirit and scope of the disclosure.

Additional features and advantages of the disclosure will be set forthin the description which follows, and in part will be obvious from thedescription, or can be learned by practice of the principles disclosedherein. The features and advantages of the disclosure can be realizedand obtained by means of the instruments and combinations particularlypointed out in the appended claims. These and other features of thedisclosure will become more fully apparent from the followingdescription and appended claims, or can be learned by the practice ofthe principles set forth herein.

It will be appreciated that for simplicity and clarity of illustration,where appropriate, reference numerals have been repeated among thedifferent figures to indicate corresponding or analogous elements. Inaddition, numerous specific details are set forth in order to provide athorough understanding of the embodiments described herein. However, itwill be understood by those of ordinary skill in the art that theembodiments described herein can be practiced without these specificdetails. In other instances, methods, procedures and components have notbeen described in detail so as not to obscure the related relevantfeature being described. The drawings are not necessarily to scale andthe proportions of certain parts may be exaggerated to better illustratedetails and features. The description is not to be considered aslimiting the scope of the embodiments described herein.

Subterranean hydraulic fracturing is conducted to increase or“stimulate” production from a hydrocarbon well. To conduct a fracturingprocess, pressure is used to pump fracturing fluids, including some thatcontain propping agents (“proppants”), down-hole and into a hydrocarbonformation to split or “fracture” the rock formation along veins orplanes extending from the well-bore. Once the desired fracture isformed, the fluid flow is reversed and the liquid portion of thefracturing fluid is removed. The proppants are intentionally left behindto stop the fracture from closing onto itself due to stresses within theformation. The proppants thus “prop-apart”, or support the opening ofthe fracture, yet remain highly permeable to hydrocarbon fluid flowsince they form a packed bed of particles with interstitial void spaceconnectivity.

To begin a fracturing process, at least one perforation is made at aparticular down-hole location through the well into a subterraneanformation, e.g. through a wall of at least one casing section, toprovide fluid communication between the wellbore interior and theformation.

One challenge in maintaining fluid communication through theperforations is that the size of the perforations (aperture size oraperture diameter) in the wellbore casing sections begins to change asthe edges erode. These erosions introduce uncertainties in otherwisecontrollable parameters, such as fluid pressure and flow rates. Aspectsof the disclosed technology address these challenges by providingsolutions for preventing erosion to perforation edges through the use oferosion resistant inserts. Additionally, aspects of the disclosedtechnology provide techniques for improving the perforation process, forexample, by providing selectively removable plugs that are disposedwithin the inserts and which can be removed to form fluid communicationchannels without the use of perforating guns.

In some implementations, the disclosed technology encompasseswear-resistant inserts that are disposed around the peripheral edge ofthe perforations to arrest erosive enlargement that can occur duringhydraulic fracturing treatment. The inserts can be filled with aselectively removable plug, for example, that can be removed to openfluid communication holes (perforations) between the wellbore interiorand the outside formation. Use of removable plugs can be used toeliminate the need of running perforating guns inside the casing, aswell as surface wireline equipment that is required to operate theperforating guns.

In practice, casing sections of a casing string are prepared beforebeing run downhole. This process includes the creation of perforationsin the wall of various casing sections, and the installation ofwear-resistant sealed inserts around the edges of the perforations. Theinserts may be constructed of different types of wear-resistantmaterials, for example, including but not limited to: tool steels, metalnitrides, metal carbides, hard chromium, cemented tungsten carbide, orceramics. Moreover, the inserts may be coated or hard-faced with powdersor particulates, including diamond, through various processes such asthermal spray coating, chemical vapor deposition, or electroplating.Regardless of the material selected or process employed, the keyrequirement for the insert is surface hardness, which should be equal toor above 40 Rockwell C (40 HRC, approximately 400 Vickers scale).Depending on the desired implementation, inserts may be affixed byvarious means, including but not limited to: welding, brazing,adhesives, threads, shrink-fits, press-fits, glass-to-metal seals,and/or ceramic-to-metal seals, and the like. In some instances, theinserts can be disposed in particular angular pattern and/orlongitudinal spading to fit specific extraction needs or scenarios. Forexample, the angular pattern may simply be zero degrees (i.e., allinserts are co-linear down the length of the casing) or may be someother phasing such as 2@180 degrees, 3@120 degrees, 6@60 degrees, and soforth. Moreover, the longitudinal spacing may be a few inches within asingle perforation cluster up to several feet to enable separation ofone cluster to another.

Once the inserts have been installed, a removable plugging material canbe inserted to seal an interior volume of the casing string. Asdiscussed in further detail below, plugs can be made of differentmaterials, and can be installed in different configurations, dependingon the desired removal process that is to be implemented.

The disclosure now turns to FIGS. 1A and 1B provide a brief introductorydescription of the larger systems that can be employed to practice theconcepts, methods, and techniques disclosed herein. A more detaileddescription of the methods and systems for implementing the improvedsemblance processing techniques of the disclosed technology will thenfollow.

FIG. 1A shows an illustrative drilling environment 100. Withinenvironment 100, drilling platform 102 supports derrick 104 havingtraveling block 106 for raising and lowering drill string 108. Kelly 110supports drill string 108 as it is lowered through rotary table 112.Drill bit 114 is driven by a downhole motor and/or rotation of drillstring 108. As bit 114 rotates, it creates a borehole 116 that passesthrough various formations 118. Pump 120 circulates drilling fluidthrough a feed pipe 122 to kelly 110, downhole through the interior ofdrill string 108, through orifices in drill bit 114, back to the surfacevia the annulus around drill string 108, and into retention pit 124. Thedrilling fluid transports cuttings from the borehole into pit 124 andaids in maintaining borehole integrity.

Downhole tool 126 can take the form of a drill collar (i.e., athick-walled tubular that provides weight and rigidity to aid thedrilling process) or other arrangements known in the art. Further,downhole tool 126 can include various sensor and/or telemetry devices,including but not limited to: acoustic (e.g., sonic, ultrasonic, etc.)logging tools and/or one or more magnetic directional sensors (e.g.,magnetometers, etc.). In this fashion, as bit 114 extends the boreholethrough formations 118, the bottom-hole assembly (e.g., directionalsystems, and acoustic logging tools) can collect various types oflogging data. For example, acoustic logging tools can includetransmitters (e.g., monopole, dipole, quadrupole, etc.) to generate andtransmit acoustic signals/waves into the borehole environment. Theseacoustic signals subsequently propagate in and along the borehole andsurrounding formation and create acoustic signal responses or waveforms,which are received/recorded by evenly spaced receivers. These receiversmay be arranged in an array and may be evenly spaced apart to facilitatecapturing and processing acoustic response signals at specificintervals. The acoustic response signals are further analyzed todetermine borehole and adjacent formation properties and/orcharacteristics.

For purposes of communication, a downhole telemetry sub 128 can beincluded in the bottom-hole assembly to transfer measurement data tosurface receiver 130 and to receive commands from the surface. In someimplementations, mud pulse telemetry may be used for transferring toolmeasurements to surface receivers and receiving commands from thesurface; however, other telemetry techniques can also be used, withoutdeparting from the scope of the disclosed technology. In someembodiments, telemetry sub 128 can store logging data for laterretrieval at the surface when the logging assembly is recovered. Theselogging and telemetry assemblies consume power, which must often berouted through the directional sensor section of the drill string,thereby producing stray EM fields which interfere with the magneticsensors.

At the surface, surface receiver 130 can receive the uplink signal fromdownhole telemetry sub 128 and can communicate the signal to dataacquisition module 132. Module 132 can include one or more processors,storage mediums, input devices, output devices, software, and the likeas described in further detail below. Module 132 can collect, store,and/or process the data received from tool 126 as described herein.

At various times during the drilling process, drill string 108 may beremoved from the borehole as shown in example environment 101,illustrated in FIG. 1B. Once drill string 108 has been removed, loggingoperations can be conducted using a downhole tool 134 (i.e., a sensinginstrument tool) suspended by a conveyance 142. In one or moreembodiments, the conveyance 142 can be a cable having conductors fortransporting power to the tool and telemetry from the tool to thesurface. Downhole tool 134 may have pads and/or centralizing springs tomaintain the tool near the central axis of the borehole or to bias thetool towards the borehole wall as the tool is moved downhole or uphole.

Downhole tool 134 can include various directional and/or acousticlogging instruments that collect data within borehole 116. A loggingfacility 144 includes a computer system, such as those described withreference to FIGS. 5 and 6, discussed below. In one or more embodiments,the conveyance 142 of downhole tool 134 can be at least one of wires,conductive or non-conductive cable (e.g., slickline, etc.), as well astubular conveyances, such as coiled tubing, pipe string, or downholetractor. Downhole tool 134 can have a local power supply, such asbatteries, downhole generator and the like. When employingnon-conductive cable, coiled tubing, pipe string, or downhole tractor,communication can be supported using, for example, wireless protocols(e.g. EM, acoustic, etc.), and/or measurements and logging data may bestored in local memory for subsequent retrieval.

Although FIGS. 1A and 1B depict specific borehole configurations, it isunderstood that the present disclosure is equally well suited for use inwellbores having other orientations including vertical wellbores,horizontal wellbores, slanted wellbores, multilateral wellbores and thelike. While FIGS. 1A and 1B depict an onshore operation, it should alsobe understood that the present disclosure is equally well suited for usein offshore operations. Moreover, the present disclosure is not limitedto the environments depicted in FIGS. 1A and 1B, and can also be used ineither logging-while-drilling (LWD) or measurement while drilling (MWD)operations.

FIG. 2 illustrates steps of an example process 200 for constructing awellbore casing string, according to some aspects of the disclosedtechnology. Process 200 begins with step 202 in which at least oneaperture (perforation) is inserted into at least one side wall of acasing section. In some embodiments, the size (e.g., diameter) andplacement of the aperture is based on the intended drilling application,such as based on formation or wellbore characteristics in which thecasing string is deployed. In some approaches, the aperture size can beoptimized based on characteristics of the hydraulic fracturing setup. Byknowing the size and number of apertures in a particular casing section,fluid distribution (e.g., fluid pressure, velocity, and/or flow rate)can be more accurately controlled during the hydraulic fracturingprocess.

In step 204, an insert is affixed around a periphery of the aperture.The insert can be composed of an erosion resistant material, such as atungsten carbide material, or other material that can resist erosioncaused by the ingress/egress of various drilling fluids and hydrocarbonsthrough the aperture in the casing wall. The insert may be affixed usingdifferent means, including but not limited to: welding, brazing,adhesives, threads, shrink-fits, press-fits, glass-to-metal seals,and/or ceramic-to-metal seals, and the like.

In step 206, a plug is placed within the insert. In some approaches, theplug is selectively removable, and serves to provide a temporary seal inthe casing wall, for example, while the casing string is run into thewellbore, and wellbore completion operations completed. Oncefracturing/production is commenced, the various plugs in the one or moredifferent casing sections can be selectively removed to permit fluidcommunication with the formation. Opening of fluid channels can involvethe removal of the plug in various ways. As such, the plug is comprisedof materials that break or disintegrate when exposed to heat, chemicals,and/or mechanical shock. As discussed in further detail below, the plugcan be one or more of a ceramic disc, for example, that can be shatteredwith mechanical shock (e.g., caused by an explosive device), or frompressure, heat, dissolution, or corrosive attack caused by a chemicalreaction.

FIG. 3 is a cut-away view of a casing string 300 with multiple casingsections 302 (e.g., casing sections 302A and 302B), according to someaspects of the disclosed technology. Casing string 300 includes sections302 that are joined by fitting 304. As further illustrated, each casingsection (302A, 302B) includes one or more plugged apertures(perforations) 306 (e.g., 306A, 306B, 306C, and 306D) that permitcommunication between an interior volume of casing string 300 and theexterior. It is understood that casing string 300 can have a greaternumber of casing sections, fittings and/or plugged apertures, withoutdeparting from the scope of the disclosed technology.

As discussed in further detail below, plugged apertures 306 include aninsert/plug combination that functions to seal the interior volume ofcasing string 300. Depending on the desired deployment, the plugmaterial may be designed for removal via a variety of different means,including the use of explosive charges, chemical reactions, or theapplication of pressure, for example, that results from a chemicalreaction. Additional details relating to plug removal are provided inconjunction with FIGS. 5A-6B, discussed below.

FIG. 4A illustrates cut away views (400, 401) of example inserts thatcontain plugs, according to some aspects of the disclosed technology. Inexample view 400, an interior volume of insert 402 is entirely filledwith a plugging material (plug) 404. As discussed above, plug 404 can bemade of a material that is designed to break or shatter in response tomechanical shock (e.g., a ceramic or ceramic composite material).However, in other embodiments, plug 404 can be comprised of materialsdesigned to melt in response to thermal stress, or dissolve when exposedto corrosive chemicals, e.g., chemical cutters. For example, plug 404may be comprised of a calcium composite or dolomite that is configuredto dissolve when contacted by an acid, such as hydrochloric acid, aceticacid, or the like. In example view 401, plug 406 is configured to havean empty interior volume 408.

FIG. 4B illustrates a cut away view of a wellbore 403 including a casingsection 410 having an insert 402, according to some aspects of thedisclosed technology. In the example of FIG. 4B, the exterior of casingsection 410 is surrounded by concrete 410 that, in turn, is adjacent toa formation 407. In this example, it is understood that casing section410 can represent only a single casing section from among multiplesections forming a casing string extending down wellbore 403.

Casing section 410 includes an insert 402 that is configured to preventerosion of casing section 410 once fluid communication has beenestablished between wellbore 403 and formation 407. To establish thiscommunication, plug 404 can be selectively removed from insert 402, forexample, to permit fracturing fluids to be pumped out of wellbore 403and into formation 407, as well as to permit hydrocarbons to flow backinto wellbore 403 from formation 407. As discussed in further detailbelow with respect to FIGS. 5A-6B, plug 404 may be selectively removedusing signals sent from the surface that are designed to cause theremoval of plug 404. e.g., via mechanical force, heat, pressure and/orchemical erosion, etc.

FIG. 5A is a cut away view a wellbore 500 utilizing a casing string 504in which a detonating cord 516 is configured to remove a casing plug508, according to some aspects of the disclosed technology. In theexample of FIG. 5A, a centralizer 514 is disposed on an outside surfaceof casing string 504, within cement layer 506. In this configuration,centralizer 514 is configured to house plug 512, as well as a detonatingcord 516, which can be used to selectively remove exterior plug 512 andcasing plug 508, for example, to permit fluid communication betweenwellbore 500 and formation 510.

FIG. 5B is a cut away view of a wellbore 501 utilizing a casing stringin which an explosive device 518 (e.g., shape charge and/or detonatingcord) are configured to remove an interior casing plug 509, and exteriorplug 513. according to some aspects of the disclosed technology. Similarto the example of FIG. 5A, a centralizer 514 is disposed on an outsidesurface of casing string 504, within cement layer 506. In thisconfiguration, centralizer 514 is configured to house explosive device518, which can be used to selectively remove exterior plug 513 andcasing plug 509, for example, to permit fluid communication betweenwellbore 501 and formation 510.

FIG. 6A is a cut away view of a wellbore 600 utilizing a casing string604 in which an erosive chemical containment device 620 is configured toremove a casing plug, according to some aspects of the disclosedtechnology. In this configuration, chemical containment device 620 isconfigured to be selectively activated, for example, using a remotelyactivate chemical release device 612, that is disposed adjacent tochemical containment device 620. For example, activation of the remotelyactivated chemical release device 621 can cause chemical containmentdevice 620 to rupture, thereby exposing casing plug 609 and exteriorplug 612 to chemically induced pressure, heat, or erosion (e.g., usingan acid). As such, removal of casing plug 609 and exterior plug 615 canbe remotely controlled in order to facilitate fluid communicationbetween wellbore 600 and formation 610.

FIG. 6B is a cut away view of a wellbore 601 utilizing a casing stringin which multiple chemical containment devices 618A, 618B are configuredto facilitate removal of plugs 609, 615, according to some aspects ofthe disclosed technology.

In this configuration, chemical containment devices 618A, 618B areconfigured to be selectively activated, for example, using a remotelyactivate chemical release device 622. Activation of chemical releasedevice 622 can cause chemical containment devices 618A, 618B to ruptureto permit a mixing of the chemicals contained therein. In some aspects,mixing of the contents of chemical containment devices 618A, 618B can beused to cause heat (e.g., through a thermal chemical reaction) and/orpressure (e.g., through an acid/base reaction) that is sufficient tobreak (or dissolve) plugs 609 and/or 615.

In some aspects, an acidic chemical cutter, such as bromine tri-fluoridemay be used to corrode or dissolve the plug; however, it is understoodthat other chemicals or chemical combinations may be used, withoutdeparting from the scope of the disclosed technology. By way of example,an acid such as hydrochloric acid, acetic acid and/or formic acid may beused to dissolve calcium carbonate or dolomite type plugs. It isunderstood that the selection of chemical cutter can be based on amaterial of the plug used, which may vary, depending on the desiredimplementation.

FIG. 7 illustrates an exemplary computing system 700 for use withexample tools and systems (e.g., tool 126). The more appropriateembodiment will be apparent to those of ordinary skill in the art whenpracticing the present technology. Persons of ordinary skill in the artwill also readily appreciate that other system embodiments are possible.

Specifically, FIG. 7 illustrates system architecture 700 wherein thecomponents of the system are in electrical communication with each otherusing a bus 705. System architecture 700 can include a processing unit(CPU or processor) 710, as well as a cache 712, that are variouslycoupled to system bus 705. Bus 705 connects various system componentsincluding system memory 715, (e.g., read only memory (ROM) 720 andrandom-access memory (RAM) 725), to processor 710. System architecture700 can include a cache of high-speed memory connected directly with, inclose proximity to, or integrated as part of the processor 710. Systemarchitecture 700 can copy data from the memory 715 and/or the storagedevice 730 to the cache 712 for quick access by the processor 710. Inthis way, the cache can provide a performance boost that avoidsprocessor 710 delays while waiting for data. These and other modules cancontrol or be configured to control the processor 710 to perform variousactions. Other system memory 715 may be available for use as well.Memory 715 can include multiple different types of memory with differentperformance characteristics. Processor 710 can include anygeneral-purpose processor and a hardware module or software module, suchas module 1 (732), module 2 (734), and module 3 (736) stored in storagedevice 730, configured to control processor 710 as well as aspecial-purpose processor where software instructions are incorporatedinto the actual processor design. Processor 710 may essentially be acompletely self-contained computing system, containing multiple cores orprocessors, a bus, memory controller, cache, etc. A multi-core processormay be symmetric or asymmetric.

To enable user interaction with the computing system architecture 700,input device 745 can represent any number of input mechanisms, such as amicrophone for speech, a touch-sensitive screen for gesture or graphicalinput, keyboard, mouse, motion input, and so forth. An output device 742can also be one or more of a number of output mechanisms. In someinstances, multimodal systems can enable a user to provide multipletypes of input to communicate with the computing system architecture700. The communications interface 740 can generally govern and managethe user input and system output. There is no restriction on operatingon any particular hardware arrangement and therefore the basic featureshere may easily be substituted for improved hardware or firmwarearrangements as they are developed.

Storage device 730 is a non-volatile memory and can be a hard disk orother types of computer readable media which can store data that areaccessible by a computer, such as magnetic cassettes, flash memorycards, solid state memory devices, digital versatile disks, cartridges,random access memories (RAMs) 735, read only memory (ROM) 720, andhybrids thereof.

Storage device 730 can include software modules 732, 734, 736 forcontrolling the processor 710. Other hardware or software modules arecontemplated. The storage device 730 can be connected to the system bus705. In one aspect, a hardware module that performs a particularfunction can include the software component stored in acomputer-readable medium in connection with the necessary hardwarecomponents, such as the processor 710, bus 705, output device 742, andso forth, to carry out various functions of the disclosed technology.

Embodiments within the scope of the present disclosure may also includetangible and/or non-transitory computer-readable storage media ordevices for carrying or having computer-executable instructions or datastructures stored thereon. Such tangible computer-readable storagedevices can be any available device that can be accessed by a generalpurpose or special purpose computer, including the functional design ofany special purpose processor as described above. By way of example, andnot limitation, such tangible computer-readable devices can include RAM,ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storageor other magnetic storage devices, or any other device which can be usedto carry or store desired program code in the form ofcomputer-executable instructions, data structures, or processor chipdesign. When information or instructions are provided via a network oranother communications connection (either hardwired, wireless, orcombination thereof) to a computer, the computer properly views theconnection as a computer-readable medium. Thus, any such connection isproperly termed a computer-readable medium. Combinations of the aboveshould also be included within the scope of the computer-readablestorage devices.

Computer-executable instructions include, for example, instructions anddata which cause a general-purpose computer, special purpose computer,or special purpose processing device to perform a certain function orgroup of functions. Computer-executable instructions also includeprogram modules that are executed by computers in stand-alone or networkenvironments. Generally, program modules include routines, programs,components, data structures, objects, and the functions inherent in thedesign of special-purpose processors, etc. that perform particular tasksor implement particular abstract data types. Computer-executableinstructions, associated data structures, and program modules representexamples of the program code means for executing steps of the methodsdisclosed herein. The particular sequence of such executableinstructions or associated data structures represents examples ofcorresponding acts for implementing the functions described in suchsteps.

Other embodiments of the disclosure may be practiced in networkcomputing environments with many types of computer systemconfigurations, including personal computers, hand-held devices,multi-processor systems, microprocessor-based or programmable consumerelectronics, network PCs, minicomputers, mainframe computers, and thelike. Embodiments may also be practiced in distributed computingenvironments where tasks are performed by local and remote processingdevices that are linked (either by hardwired links, wireless links, orby a combination thereof) through a communications network. In adistributed computing environment, program modules may be located inboth local and remote memory storage devices.

The various embodiments described above are provided by way ofillustration only and should not be construed to limit the scope of thedisclosure. For example, the principles herein apply equally tooptimization as well as general improvements. Various modifications andchanges may be made to the principles described herein without followingthe example embodiments and applications illustrated and describedherein, and without departing from the spirit and scope of thedisclosure. Claim language reciting “at least one of” a set indicatesthat one member of the set or multiple members of the set satisfy theclaim.

STATEMENTS OF THE DISCLOSURE

Statement 1: a casing string configured for facilitating hydrocarbonextraction from a wellbore, the casing string including: at least onecasing section, an aperture disposed on a surface of the of the at leastone casing section, an insert affixed around a periphery of theaperture; and a plug disposed within the insert, wherein the plug isconfigured to be selectively removable to allow fluid communicationbetween an interior volume of the casing string and an exterior of thecasing string adjacent to a geologic formation.

Statement 2: the casing string of statement 1, wherein the insert isconfigured to prevent erosion of the internal edge of the aperture inorder to maintain a diameter of the aperture.

Statement 3: the casing string of any of statements 1-2, wherein theinsert comprises a carbide composite.

Statement 4: the casing string of any of statements 1-3, wherein theplug is configured to be removed from the insert by an explosive charge.

Statement 5: the casing string of any of statements 1-4, wherein theplug is configured to be removed from the insert by heat.

Statement 6: the casing string of any of statements 1-5, wherein theplug is configured to dissolve upon contact with a chemical cutter.

Statement 7: the casing string of any of statements 1-6, wherein thechemical solution comprises bromine tri-fluoride.

Statement 8: the casing string of any of statements 1-7, wherein thechemical solution comprises an acid.

Statement 9: the casing string of any of statements 1-8, wherein theplug comprises zinc.

Statement 10: the casing string of any of statements 1-9, wherein theplug comprises aluminum.

Statement 11: the casing string of any of statements 1-10, wherein theplug comprises ceramic and calcium carbonate.

Statement 12: a method for constructing a casing string configured forfacilitating hydrocarbon extraction from a wellbore, the casing stringincluding: inserting an aperture in at least one casing section, whereinthe aperture is disposed on a surface of the of the at least one casingsection; affixing an insert around a periphery of the aperture; andplacing a plug within the insert, wherein the plug is configured to beselectively removable to allow fluid communication between an interiorvolume of the casing string and an exterior of the casing stringadjacent to a geologic formation.

Statement 13: the method of statement 12, wherein the insert isconfigured to prevent erosion of the internal edge of the aperture inorder to maintain a diameter of the aperture.

Statement 14: the method of any of statements 12-13, wherein the insertcomprises a carbide composite.

Statement 15: the method of any of statements 12-14, wherein the plug isconfigured to be removed from the insert by an explosive charge.

Statement 16: the method of any of statements 12-15, wherein the plug isconfigured to be removed from the insert by heat.

Statement 17: the method of any of statements 12-16, wherein the plug isconfigured to dissolve upon contact with a chemical cutter.

Statement 18: the method of any of statements 12-17, wherein thechemical solution comprises bromine tri-fluoride.

Statement 19: the method of any of statements 12-18, wherein thechemical solution comprises an acid.

Statement 20: a wellbore casing section, comprising: at least oneaperture disposed on a surface of the casing section; an insert affixedaround a periphery of the aperture; and a plug disposed within theinsert, wherein the plug is configured to be selectively removable tofacilitate communication between an interior volume of the casingsection and an exterior of the casing section.

1. A casing string configured for facilitating hydrocarbon extractionfrom a wellbore, the casing string comprising: at least one casingsection; an aperture disposed on a surface of the of the at least onecasing section; an insert affixed around a periphery of the aperture;and a plug disposed within the insert, wherein the plug is configured tobe selectively removable to allow fluid communication between aninterior volume of the casing string and an exterior of the casingstring adjacent to a geologic formation.
 2. The casing string of claim1, wherein the insert is configured to prevent erosion of the internaledge of the aperture in order to maintain a diameter of the aperture. 3.The casing string of claim 1, wherein the insert comprises a carbidecomposite.
 4. The casing string of claim 1, wherein the plug isconfigured to be removed from the insert by an explosive device.
 5. Thecasing string of claim 1, wherein the plug is configured to be removedfrom the insert by heat.
 6. The casing string of claim 1, wherein theplug is configured to dissolve upon contact with a chemical cutter. 7.The casing string of claim 6, wherein the chemical solution comprisesbromine tri-fluoride.
 8. The casing string of claim 6, wherein thechemical solution comprises an acid.
 9. The casing string of claim 1,wherein the plug comprises zinc.
 10. The casing string of claim 1,wherein the plug comprises aluminum.
 11. The casing string of claim 1,wherein the plug comprises ceramic, calcium carbonate, or dolomite. 12.A method for constructing a casing string configured for facilitatinghydrocarbon extraction from a wellbore, the casing string comprising:inserting an aperture in at least one casing section, wherein theaperture is disposed on a surface of the of the at least one casingsection; affixing an insert around a periphery of the aperture; andplacing a plug within the insert, wherein the plug is configured to beselectively removable to allow fluid communication between an interiorvolume of the casing string and an exterior of the casing stringadjacent to a geologic formation.
 13. The method of claim 12, whereinthe insert is configured to prevent erosion of the internal edge of theaperture in order to maintain a diameter of the aperture.
 14. The methodof claim 12, wherein the insert comprises a carbide composite.
 15. Themethod of claim 12, wherein the plug is configured to be removed fromthe insert by an explosive device.
 16. The method of claim 12, whereinthe plug is configured to be removed from the insert by heat.
 17. Themethod of claim 12, wherein the plug is configured to dissolve uponcontact with a chemical cutter.
 18. The method string of claim 17,wherein the chemical solution comprises bromine tri-fluoride.
 19. Themethod string of claim 17, wherein the chemical solution comprises anacid.
 20. A wellbore casing section, comprising: at least one aperturedisposed on a surface of the casing section; an insert affixed around aperiphery of the aperture; and a plug disposed within the insert,wherein the plug is configured to be selectively removable to facilitatecommunication between an interior volume of the casing section and anexterior of the casing section.